The field of the present invention relates to the protection of maintenance personnel and the like in relation to generated power provided by a train vehicle that is decelerating by regenerative braking and thereby supplying undesired power back to the power supply rail.
It is known in the prior art relating to train vehicle control apparatus to control the operation of one or more train vehicles moving along a track by using a control signal transmitted into the track and including modulated information, such as desired speed or the like, for controlling the operation of the train vehicle. A signal receiver carried by the train vehicle including a detector to remove the modulated information from the transmitted signal was operative to provide this modulated information for controlling the train vehicle as desired. An example of such a control system is shown by U.S. Pat. Nos. 3,532,877 and Re. 27,472 of G. M. Thorne-Booth and U.S. Pat. No. 3,551,889 of C. S. Miller.
It is also known in the prior art to control the propulsion motor current determining chopper operation for each car vehicle of a plural vehicle train by a provided control signal transmitted to each vehicle car of that train, as shown by U.S. Pat. No. 3,707,659 of H. C. Appelo. It is known to modulate the excitation voltage for the purpose of communicating with a train vehicle moving along a track as shown by U.S. Pat. No. 3,743,935 of G. L. Alt.
Prior art regenerative braking arrangements for a train vehicle using direct current choppers, where the power supply may be relatively non-receptive to receiving the regenerated power are shown by U.S. Pat. No. 3,657,625 of L. G. Miller et al. and U.S. Pat. No. 3,593,089 of H. C. Appelo, with the regenerative power generated being supplied to the power supply in relation to the power receptivity of the power supply.
It is known to control the dynamic braking effort provided by train vehicle motors in relation to an incoming control signal representing the motor current necessary to obtain the desired braking effort, as shown by U.S. Pat. No. 3,543,113 of L. G. Miller.
The propulsion control system takes power from the third rail and operates with the motor as a motor, whereas the regenerative braking control system operates with the motor as a generator to put electrical power back into the third rail. The associated switch gear operates with one of the propulsion control system or the regenerative brake control system to determine which way the involved electrical power will flow in relation to the third rail.
In the Westinghouse Engineer for September 1970 at pages 143 to 149, a published article entitled "Propulsion Control For Passenger Train Provides High Speed Service" describes motoring and dynamic braking operations of train vehicle motors. In the Westinghouse Engineer for March 1973 at pages 34 to 41, a published article entitled "Alternative Systems For Rapid Transit Propulsion And Electrical Braking" describes a thyristor system for controlling the motoring mode and the braking mode operations of train vehicle motors, including regenerative braking.